Having trained as a mathematician I naturally reach for an envelope whenever I need to work out some quick equations or sort out some rough numbers while processing business transactions. These pieces of paper all add to the mess flying around my desktop. So the thought of being able to do this with a Tablet+Pen in OneNote is turning me further towards the Tablet.

Update: The is also a very cool looking tablet maths app from xThink. Some details on evalution version here.